Such an apparatus is known, for instance, from document DE 41 390 29 A1. In this apparatus, a gas flows axially from an outflow opening of a gas-delivering device to an electrode, and the electrode is positioned in front of the opening, so that a plasma tends to be produced in a direction axial to the gas-delivering device. Especially when an endoscopic operation is being performed within a body cavity, i.e. under confined conditions, it is difficult to coagulate tissue sites situated at the side, in a direction radial with respect to the opening.
The document DE 198 202 40 C2 discloses a tissue-coagulating apparatus in which the electrode is disposed entirely within a tubular probe provided with a slit-shaped opening that passes helically around its circumference, so that the delivered gas and also the plasma emerge in a direction radial to the probe. One problem here resides in manufacturing such probes, in view of the confined spatial relationships. Another is that the probe material can relatively easily be damaged by the high temperatures of the plasma.